The present invention relates to a technique of buffering access data in a memory system for performing access control between an external interface and a nonvolatile memory in response to an access request from the outside and, for example, to a technique effectively applied to a flash memory card.
A flash memory card has a flash memory and a controller. Since the operation speed, particularly, writing or rewriting operation speed of the flash memory is lower than operation speed of a host connected to the flash memory card, the controller has a buffer memory in order to absorb the difference between the operation speeds. In response to a write request from the outside, the controller controls to input write data from the outside to the buffer memory and write the input data into the flash memory. In response to a read request from the outside, the controller temporarily stores data read out from the flash memory into the buffer memory and outputs the stored data to the outside. As a conventional buffer memory, an SRAM (Static Random Access Memory) of a relatively small capacity, a static latch, or the like is often employed.